This application claims the benefit of priority to Japanese application No. 2002-140623, filed May 15, 2002, the contents of which are herein incorporated by reference.
In general, the present invention relates to a system including a data-transmitting apparatus having a data-encoding apparatus adopting a data-encoding method for encoding data to be transmitted in a real space and including a data-receiving apparatus having a data-decoding apparatus adopting a data-decoding method for decoding the transmitted data obtained as a result of encoding, as well as relates to computer programs implementing the data-encoding method and the data-decoding method. More particularly, the present invention relates to a system including a data-transmitting apparatus having a data-encoding apparatus adopting a data-encoding method for encoding data to be transmitted as an optical signal representing a light-blinking pattern obtained as a result of encoding and including a data-receiving apparatus having a data-decoding apparatus adopting a data-decoding method for decoding the transmitted optical signal, as well as relates to computer programs implementing the data-encoding method and the data-decoding method.
To put it in detail, the present invention relates to a system including a data-transmitting apparatus having a data-encoding apparatus adopting a data-encoding method for encoding data to be transmitted into a light-blinking pattern of light-emitting sources laid out to form a two-dimensional matrix and including a data-receiving apparatus having a data-decoding apparatus adopting a data-decoding method for decoding the transmitted light-blinking pattern into the original data, as well as relates to computer programs implementing the data-encoding method and the data-decoding method. More particularly, the present invention relates to a system including a data-transmitting apparatus having a data-encoding apparatus adopting a data-encoding method for encoding data to be transmitted into a light-blinking pattern of light-emitting sources laid out to form a two-dimensional matrix and for transmitting the light-blinking pattern at a bit rate according to a distance from the data-transmitting apparatus to a data-receiving apparatus and including the data-receiving apparatus having a data-decoding apparatus adopting a data-decoding method for decoding the transmitted light-blinking pattern, as well as relates to computer programs implementing the data-encoding method and the data-decoding method.
In this present day of an advanced information-processing technology and an advanced information communication technology, information apparatus such as personal computers and portable information terminals universally exist in the real world such as offices and homes. In such an environment, the apparatus are connected to each other so that implementations of a ubiquitous computing system and an AR (Augmented Reality) system can be expected. The ubiquitous computing system is a system for obtaining desired information. On the other hand, the AR system is a system actively using circumstances in the real world. The circumstances in the real world include matters of the real world and the position of the user.
The concept of the ubiquitous computing is introduced to make the environment of a computer unchanged without regard to the place at which the user is present. Since the concept of the ubiquitous computing brings about a computing capability at any time and at any place, an ultimate ubiquitous computing system does not necessarily require an information terminal such as a computer, a PDA (Personal Digital Assistant) and a hand phone.
In operations carried out by the user to specify a computer or a peripheral apparatus as a data transmission destination within a network and to obtain a circumstance of the real world, however, the user must know the name of a partner even if the partner exists right in front of the user. An example of the peripheral apparatus is a transmission target such as a user terminal. Examples of the circumstance of the real world include the position of the user and information related to a real-world object. Instead of knowing the name of a partner, the user must know a resource identifier such as an ID unique to the partner apparatus and/or the network address of the partner apparatus, a host name or a URL/URI. That is to say, in the operations carried out by the user, collaboration with the computer exists only in an indirect form and there is a lack of an intuitive sense.
As a technology for transmitting the identification of the user and acquiring a real-world circumstance such as the position of the user without following such a complicated-procedure, there have been proposed techniques of utilizing real-world computing such as a technique of using visual codes including cyber codes and RF tags. By adopting any of these techniques, it is not necessary for the user to make an access to the network in a conscious manner. Instead, the user is capable of obtaining information related to an object from the object ID, which is automatically picked up.
For example, for an identification such as a visual code or an RF tag, the function of an application or the like, an apparatus ID, a network address, a host name, a URL or other object-related information is registered in advance. Then, in response to a cyber code recognized from a picture taken by a camera, the computer executes the registered application. For example, the computer activates a mail program. Then, the computer searches for a network address of the partner on the basis of the recognized ID to automatically establish a connection with the partner and to make an access to the resource indicated by the recognized URL.
If visual identification information such as a visual code is used, however, the size of the code changes in accordance with the distance. That is to say, the size of the code of an object located far away is small so that it is necessary to form a code having a large pattern for recognizing an object located far away. In other words, an information transmission method based on this technique has a lack of robustness in the case of a long distance. In order to recognize a building located far away, for example, it is necessary to paste a huge code on the building and such a huge code pasted on the building is not realistic.
In addition, in the case of an RF tag, the user must orient the RF tag in a direction toward a tag-reading apparatus or must take the RF tag into contact with the tag-reading apparatus. That is to say, only an object at a short distance can be recognized and an object at a long distance cannot.
In order to solve this problem, there has been proposed a data communication system for implementing data transmissions including long-distance transmissions of data at different resolutions as disclosed in Japanese Patent Application No. 2002-57836 describing a specification of an invention, the patent of which was granted to the applicant for a patent of the present invention. In this system, data is transmitted as an optical signal for conveying identification and other data in an optical format, and is detected by using an advanced two-dimensional image sensor.
A data-transmitting apparatus employed in the above system extracts portions each having a predetermined length from a bit stream of data being transmitted and transforms each of the extracted portions into a display pattern by using a predetermined transformation table. The display pattern appears on blinking light-emitting sources such as LEDs, which in turn generate an optical signal. Thus, prior to a transmission of data, the data-transmitting apparatus encodes the data to be transmitted not into a color spatial pattern such as a visual code, but into a time-series optical signal such as a blinking pattern, which does not change in accordance with the distance between the data-transmitting apparatus and a data-receiving apparatus.
The image sensor serving as a receiver employed in the data-receiving apparatus comprises a countless number of light-receiving devices (that is, pixels), which are arranged to form a two-dimensional array as is the case with a CMOS (Complementary Metal Oxide Semiconductor) sensor and a CCD (Charge Coupled Device) sensor. The image sensor decodes the received optical signal and its spatial information at all the pixels. As an ordinary camera, the image sensor is used for shooting a scene and is capable of receiving an optical signal in its field of vision even if the optical signal is transmitted by a data-transmitting apparatus located far away from the data-receiving apparatus.
Assume for example that a transmitter including light-emitting units implemented typically by at least two LEDs laid out at predetermined physical locations is installed for a real-world object such as a piece of indoor furniture, an indoor electrical appliance or an outdoor building. The transmitter extracts portions each having a predetermined length from a bit stream of data being transmitted and transforms each of the extracted portions into a blinking display pattern by using a predetermined transformation table. The blinking display pattern puts the light-emitting units in a blinking state, transmitting the data. On the other hand, the receiver has a two-dimensional light-receiving surface used as a light-receiving unit capable of decoding the received blinking pattern into the original data on the basis of a transformation table and capable of recognizing spatial information on the real-world object on the basis of the blinking pattern""s detection location on the two-dimensional light-receiving surface.
Transmitted data output by the transmitter includes a resource identification such as the ID of the object, its network address, a host name, a URL or a URI, or other object-related information.
Applications of the data communication system using an optical signal include a system in which a number of LEDs is arranged to form a matrix in the data-transmitting apparatus and the optical signal is transmitted by the data-transmitting apparatus as a two-dimensional blinking pattern appearing on the matrix of LEDs.
In the case of a system using such a two-dimensional blinking pattern as transmission media, however, the distance between the data-transmitting apparatus and the data-receiving apparatus becomes a problem. If the image sensor employed in the data-receiving apparatus has a resolution insufficient for the distance between the data-transmitting apparatus and the data-receiving apparatus, for example, the data-receiving apparatus is not capable of receiving information at all. That is to say, the data-receiving apparatus is not capable of receiving any information unless the data-receiving apparatus is taken to a location close enough to the data-transmitting apparatus so that the state of blinking of the LED matrix in the data-transmitting apparatus can be recognized completely. In other words, there is a lack of robustness in the case of a long distance.
In such a case, the data-receiving apparatus is taken to a location close enough to the data-transmitting apparatus in order to solve the problem. In actuality, however, the person carrying the data-receiving apparatus approaches the data-transmitting apparatus only to find out that the transmitted information is information not required at all by the person so that the person becomes aware of the fact that the move to approach the data-transmitting apparatus has been wasteful. In a word, in a system using a two-dimensional blinking pattern as transmission media, there is a lack of robustness in the case of a long distance.
It is thus an object of the present invention addressing the problems described above to provide a data-transmitting apparatus having a data-encoding apparatus adopting a data-encoding method capable of well encoding data to be transmitted as an optical signal representing a light-blinking pattern obtained as a result of encoding, relates to a data-receiving apparatus having a data-decoding apparatus adopting a data-decoding method capable of well decoding the transmitted optical signal, relates to computer programs implementing the data-encoding method and the data-decoding method as well as relates to a storage medium for storing the computer programs.
It is another object of the present invention addressing the problems described above to provide a data-transmitting apparatus having a data-encoding apparatus adopting a data-encoding method capable of well encoding data to be transmitted into a blinking pattern of light-emitting sources laid out to form a two-dimensional matrix, relates to a data-receiving apparatus having a data-decoding apparatus adopting a data-decoding method capable of well decoding the blinking pattern received from the data-transmitting apparatus, relates to computer programs implementing the data-encoding method and the data-decoding method as well as relates to a storage medium for storing the computer programs.
In accordance with a first aspect of the present invention, there is provided a data-encoding apparatus or a data-encoding method used for mapping data onto a pattern in a two-dimensional picture space, including:
space-disassembling means for or a space-disassembling step of disassembling the two-dimensional picture space into a plurality of picture sub-spaces having resolution different from each other; and
data-mapping means for or a data-mapping step of mapping the data onto a pattern in any one of the picture sub-spaces that has a resolution suitable for the data.
In accordance with a second aspect of the present invention, there is provided a data-decoding apparatus or a data-decoding method used for decoding data obtained as a result of a mapping process in a two-dimensional picture space, including:
space-disassembling means for or a space-disassembling step of disassembling the two-dimensional picture space into one or more picture sub-spaces having resolution different from each other; and
data-decoding means for or a data-decoding step of decoding the data obtained as a result of a mapping process in any one of the picture sub-spaces that has a resolution suitable for the data.
Applications of the data communication system using an optical signal include a system in which a number of LEDs is arranged to form a matrix in the data-transmitting apparatus and the optical signal is transmitted by the data-transmitting apparatus as a two-dimensional blinking pattern appearing on the matrix of LEDs. In the case of a system using such a two-dimensional blinking pattern as transmission media, however, the distance between the data-transmitting apparatus and the data-receiving apparatus becomes a problem. If the image sensor employed in the data-receiving apparatus has a resolution insufficient for the distance between the data-transmitting apparatus and the data-receiving apparatus, for example, the data-receiving apparatus is not capable of receiving information at all.
In order to solve the problem described above, in accordance with the present invention, the two-dimensional picture space is divided into a plurality of resolution sub-spaces having resolution different from each other, and data is mapped onto a pattern in a subspace with a resolution suitable for the data. Thus, a data-receiving apparatus with a resolution thereof reduced to an insufficient level due to a long distance between the data-receiving apparatus and the data-transmitting apparatus is capable of reading a two-dimensional blinking pattern obtained as a result of a process carried out by the data-transmitting apparatus to encode the data to be transmitted in a sub-space at a low-resolution. By observation of a two-dimensional picture space at a short distance between the data-receiving apparatus and the data-transmitting apparatus at a sufficient resolution due to the short distance, on the other hand, the data-receiving apparatus is capable of reading a two-dimensional blinking pattern resulting from a process to encode the data to be transmitted in a sub-space at high-resolution. As a result, even if a data-receiving apparatus is at a location far away from the data-transmitting apparatus, the data-receiving apparatus is capable of obtaining information to a certain degree, allowing a person carrying the data-receiving apparatus to form a judgment as to whether or not it is necessary for the person to approach the data-transmitting apparatus in order to obtain more detailed information.
In this case, the two-dimensional picture space typically comprises a plurality of light-emitting devices laid out on a two-dimensional planar surface. Thus, in the data-mapping means or at the data-mapping step, data can be mapped onto a blinking pattern having ON ratios for areas each consisting of ni light-emitting devices of the two-dimensional picture space in the picture sub-space having the ith resolution suitable for the data where the ON ratio for an area is a ratio of the number of ON light-emitting devices in the area to the total number of all light-emitting devices in the same area. In this case, for j less than k, the relation nj less than nk holds true where symbols j and k each denote a resolution whereas symbols nj or nk denotes the number of light-emitting devices in an area in a sub-space with the jth or kth resolution respectively. In addition, in the data-decoding means or at the data-decoding step, a blinking pattern having ON ratios for areas each including ni light-emitting devices of the two-dimensional picture space in the picture sub-space having the ith resolution suitable for the original data can be restored to the original data.
Furthermore, in the data-mapping means or at the data-mapping step, it is possible to determine the resolution of the picture sub-space, in which data is to be encoded, in accordance with the size of the data to be encoded.
Moreover, in the data-mapping means or at the data-mapping step, it is possible to map desired data onto a two-dimensional blinking pattern in the two-dimensional picture space""s picture sub-space at a lower resolution so that the two-dimensional blinking pattern can be observed at a low resolution insufficient for a picture sub-space with a higher resolution.
In addition, in the data-mapping means or at the data-mapping step, it is possible to map more detailed data onto a two-dimensional blinking pattern in a picture sub-space at a high resolution and to map abstracted rough data onto a two-dimensional blinking pattern in a picture sub-space at a low resolution.
Furthermore, in the data-mapping means or at the data-mapping step, it is possible to add data for correcting errors to each picture sub-space having a resolution. In such a case, the data-receiving apparatus is capable of knowing the number of errors included in information at a hierarchical layer of each resolution. If such a system is used and the number of errors detected by the data-receiving apparatus at a specific hierarchical layer is too large, it is possible to prevent a two-dimensional blinking pattern at a hierarchical layer with a frequency higher than the specific hierarchical layer from being decoded.
Moreover, in the data-mapping means or at the data-mapping step, in a process to encode data of a computer graphic, it is possible to map geometrical data of a drawing object onto a two-dimensional blinking pattern in a picture sub-space at a low resolution and texture data of the drawing object onto a two-dimensional blinking pattern in a picture sub-space at a high resolution. In addition, it is also possible to change the resolution of the picture sub-space, in which a mapping process is to be carried out, in accordance with a frequency component of the texture data.
Normally, an ordinary person will probably orient the camera employed in the data-receiving apparatus carried by the person to the right front surface of a data-transmitting apparatus, which serves as a source transmitting information of interest to the person. With the camera oriented in such a direction, a source transmitting information of no interest to the person will probably appear as a picture on an edge of the screen of the camera even if the picture of such a source is taken by the camera. With the camera oriented to the right front surface of a source transmitting information of interest to the person, the person sees the right front surface of the information-emitting source, and the data-receiving apparatus is capable of recognizing two-dimensional blinking patterns in picture sub-spaces at all resolution. That is to say, in this case, the data-receiving apparatus is capable of receiving all data of a computer graphic. Thus, a three-dimensional virtual object of the computer graphic can be reproduced from information on the three-dimensional virtual object""s contours and very fine textures, and then displayed on a monitor.
In accordance with a third aspect of the present invention, there is provided a data-transmitting apparatus used for outputting transmitted data in a format of an optical signal, including:
two-dimensional light-emitting means including a plurality of light-emitting devices arranged on a two-dimensional planar surface;
space-disassembling means for disassembling a two-dimensional picture space of blinking states of the light-emitting devices included in the two-dimensional light-emitting means into a plurality of picture subspaces having resolution different from each other; and
data-mapping means for mapping data to be transmitted onto a blinking pattern in any one of the picture sub-spaces that has a resolution suitable for the data, wherein the blinking pattern obtained as a result of a mapping process carried out by the data-mapping means is output by the light-emitting devices included in the two-dimensional light-emitting means.
In accordance with a fourth aspect of the present invention, there is provided a data-receiving apparatus used for receiving data transmitted in a format of an optical signal, including:
shooting means for shooting an optical blinking pattern spread over a two-dimensional planar surface;
space-disassembling means for disassembling a two-dimensional picture space into one or more picture subspaces having resolution different from each other; and
data-decoding means for decoding data obtained as a result of a mapping process in any one of the picture sub-spaces that has a resolution suitable for the data.
In accordance with the third and fourth aspects of the present invention, the data-transmitting apparatus disassembles a two-dimensional picture space into a plurality of picture sub-spaces having resolution different from each other, and maps data to be transmitted onto a two-dimensional blinking pattern in any one of the picture sub-spaces that has a resolution suitable for the data prior to a transmission of the blinking pattern. Thus, the data-receiving apparatus is capable of reading a two-dimensional blinking pattern obtained as a result of a mapping process carried out by the data-transmitting apparatus in a picture sub-space at a low resolution in an observation of the two-dimensional picture space at an insufficient resolution caused by the fact that the data-receiving apparatus is at a location far away from the data-transmitting apparatus. In addition, the data-receiving apparatus is capable of reading a two-dimensional blinking pattern obtained as a result of a mapping process carried out by the data-transmitting apparatus in a picture sub-space at a high resolution in an observation of the two-dimensional picture space at an sufficient resolution caused by the fact that the data-receiving apparatus is at a location close to the data-transmitting apparatus. As a result, even if a data-receiving apparatus is at a location far away from the data-transmitting apparatus, the data-receiving apparatus is capable of obtaining information to a certain degree, allowing a person carrying the data-receiving apparatus to form a judgment as to whether or not it is necessary for the person to approach the data-transmitting apparatus in order to obtain more detailed information.
In this case, the two-dimensional picture space typically comprises a plurality of light-emitting devices laid out on a two-dimensional planar surface. Thus, in the data-mapping means or at the data-mapping step, data can be mapped onto a blinking pattern having predetermined ON ratios for areas each consisting of ni light-emitting devices of the two-dimensional picture space in the picture sub-space having the ith resolution suitable for the data where the ON ratio for an area is a ratio of the number of ON light-emitting devices in the area to the total number of all light-emitting devices in the same area. In this case, for j less than k, the relation nj less than nk holds true where symbols j and k each denote a resolution whereas symbols nj or nk denotes the number of light-emitting devices in an area in a sub-space with the jth or kth resolution respectively. In addition, in the data-decoding means or at the data-decoding step, a blinking pattern having ON ratios for areas each consisting of ni light-emitting devices of the two-dimensional picture space in the picture sub-space having the ith resolution suitable for the original data can be restored to the original data.
In this case, the data-receiving apparatus may be provided with a perspective projection means for carrying out a perspective-projection process on a two-dimensional picture space""s two-dimensional blinking pattern photographed by the shooting means. If the line of sight of the shooting means toward the two-dimensional picture space is oriented in a slanting direction, the photographed perspective two-dimensional blinking pattern of the two-dimensional picture space can be transformed into a pattern of the two-dimensional picture space seen from a location right in front of the two-dimensional picture space.
In the data-transmitting apparatus, it is possible to vary the display time of a blinking pattern, which is obtained as a result of a mapping process carried out by the data-mapping means, in accordance with the resolution of the picture sub-space in which the mapping process is performed. For example, the display time of the blinking pattern is set at a large value for a picture sub-space having a high resolution. That is to say, since the data-transmitting apparatus is capable of transmitting a low-frequency portion at a low speed, that is, at a relatively small value of the ratio P (q):q, the data-receiving apparatus is capable of taking a picture in P (q) units by lengthening the exposure time. As a result, a data-receiving apparatus is capable of receiving information of a low-frequency portion transmitted by the data-transmitting apparatus even if the data-receiving apparatus is located far away from the data-transmitting apparatus and, hence, prone to insufficient exposure.
In addition, in accordance with a fifth aspect of the present invention, there is provided a computer program, which is written in a format that can be read by a computer, is prescribed for execution on a computer system for carrying out a data-encoding process to map data onto a blinking pattern in a two-dimensional image space and is characterized in that the computer program comprises:
a space-disassembling step of disassembling the two-dimensional picture space into a plurality of picture sub-spaces having resolution different from each other; and
a data-mapping step of mapping data to be transmitted onto a blinking pattern in any one of the picture sub-spaces that has a resolution suitable for the data.
Furthermore, in accordance with a sixth aspect of the present invention, there is provided a computer program, which is written in a format that can be read by a computer, is prescribed for execution on a computer system for carrying out a data-decoding process to decode data obtained as a result of a mapping process carried out in a two-dimensional image space and is characterized in that the computer program comprises:
a space-disassembling step of disassembling the two-dimensional picture space into one or more picture sub-spaces having resolution different from each other; and
a data-decoding step of decoding data obtained as a result of a mapping process in any one of the picture sub-spaces that has a resolution suitable for the data.
The computer programs according to the fifth and sixth aspects of the present invention are each a program written in a format that can be read by a computer and prescribed for carrying out a predetermined process on a computer system. In other words, by installing the computer programs according to the fifth and sixth aspects of the present invention into the computer system, collaboration functions can be exhibited by the computer system to give the same effects as the data-encoding apparatus according to the first aspect of the present invention and the data-encoding method adopted by the data-encoding apparatus as well as the data-decoding apparatus according to the second aspect of the present invention and the data-decoding method adopted by the data-decoding apparatus.
Other objects, characteristics and advantages according to the present invention will probably become obvious from a study of the following detailed descriptions of preferred embodiments of the present invention with reference to the following diagrams.